Oil such as ATF (Automatic Transmission Fluid) flows through the interior of automatic transmissions of vehicles. In the course of the oil flowing through the automatic transmissions, air may be incorporated into the oil to create oil bubbles. Oil bubbles are air covered with oil films, and thus once oil bubbles are created, there is the problem that control of the oil pressure is difficult. This is because the pressure applied to oil is reduced as a result of the air inside the oil bubbles deflating.
In order to solve the above-described problem, JP 2012-36986A discloses a structure in which a breather chamber attached to an automatic transmission has a wall with protrusions. The protrusions are configured to extinguish oil bubbles by colliding with the oil bubbles.
JP 2012-36986A is an example of related art.